Biological Molecules Flashcards
What are the four main groups of biological molecules?
Carbohydrates, proteins, lipids (fats) and DNA
What are carbohydrates, proteins and lipids all made up of?
Carbon, hydrogen and oxygen
What do proteins contain that carbohydrates, proteins and lipids don’t?
Nitrogen and sometimes sulphur
What is an organic molecule?
A molecule that contains carbon and hydrogen
What are the 2 types of carbohydrates?
Simple sugars and complex carbohydrates
What are the characteristics of sugars?
Soluble in water and sweet tasting
Name 3 simple sugars
Glucose, lactose, sucrose
Name of a single unit of sugar
Monosaccharide
Name of 2 sugar molecules joined together
Disaccharide
What chemical process do simple sugars supply energy for?
Respiration
Complex carbohydrates are made of……….
thousands of glucose molecules
What are polymers?
Large molecules made of many repeating monomers
Complex carbohydrates are storage molecules, how are they stored in both plants and animals?
Starch in plants, glycogen in animals
What are the 3 characteristics of storage molecules?
- Insoluble so won’t affect water movement
- Compact so can store lots of glucose in a small space
- Less reactive than glucose so isn’t broken down
Name a complex carbohydrate that makes up plant cell walls
Cellulose
What are proteins made up of?
Many amino acids which are joined together
How many different amino acids and proteins are there?
20 amino acids and limitless number of proteins
What are the 5 functions of proteins?
- structural molecules (collagen/keratin)
- controlling chemical reactions (enzymes)
- messenger molecules (hormones)
- combating disease (antibodies)
- transport (haemoglobin/cell membrane)
What are the 5 functions of lipids?
- energy storage
- thermal and electrical insulation
- protection of organs
- make some hormones
- essential part of cell membranes
All lipids are made up of which two types of molecules?
Fatty acids and glycerol
Saturated fatty acids = ??
FATS, these are solid at room temperature
Unsaturated fatty acids = ??
OILS, these are liquid at room temperature
Outline the 3 main steps of Benedict’s test for glucose
- Add 5cm cubed of Benedict’s solution to the liquid
- Heat, using a water bath at 60ºC
- If glucose is present = blue to brick red
Outline the 2 mains steps of the iodine test for starch
- Add 5-10 drops of iodine solution
- If starch present = brown to blue-black
What is a catalyst?
A chemical which increases the rate of a reaction without being used up itself in the reaction
What are catabolic reactions?
Breaking down large molecules into smaller products e.g. digestion
What are anabolic reactions?
Building large molecules from smaller substrates e.g. DNA synthesis)
Explain the Lock and Key theory of how enzymes work
- the substrate binds to the active site of the enzyme
- shape of active site compliments shape of substrate
- the products of the reaction don’t fit the active site as well as the substrate, so they are released
What are the benefits of binding to the active site.
- allows lower Ea than without the enzyme
- allows enzymes to increase rate of reaction
- without enzymes = slow reactions, dead organisms
